Engine starter gearing



Aug. 21, 1951 J DIGBY 2,565,170

ENGINE STARTER GEARING Filed Aug. 30, 1950 INVENTOR. WITNESS: m i 65 51$ m jazz: 1

A HNEY Patented Aug. 21, 1951 ENGINE STARTER GEARING James J. Digby, Elmira, N. Y., assignor to Bendix Aviation Corporation, a corporation of Delaware Application August 30, 1950, Serial No. 182,335

3 Claims. 1

The present invention relates to engine starter gearing, and more particularly to that type of starter drive in which a pinion is automatically traversed into and out of mesh with an engine gear.

It is an object of the present invention to provide a novel engine starter drive incorporating a torsional spring connection, which is exceptionally small and compact in comparison with standard types of drive of similar load rating.

It is another object to provide such a device in which the yielding driving connection is telescoped over the traversing connection so as to reduce the overall length of the drive.

It is another object to provide such a device in which the traversing means for the pinion comprises a screw and nut, and the reaction of the screw jack action of the screw and nut is taken by the power shaft upon which the drive is mounted.

Further objects and advantages will be apparent from the folowing description taken in connection with the accompanying drawing in which Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention.

Fig. 2 is a simiar View showing the parts in cranking position.

Fig. 3 is a section taken substantially on the line 3-3 of Fig. 1.

In Fig. 1 of the drawing there is illustrated a power shaft l on which a driving head 2 is fixedly mounted as by means of a cross pin 3. A screw shaft and pinion member 4 is slidably journalled on the power shaft l for longitudinal movement into and out of mesh with an engine gear 5, the meshing position of the pinion being defined by a stop sleeve 6 fixed in any suitable manner on the power shaft i.

Driving head 2 is provided with shoulders I and 8 formed by milling flats 9 and II oppositely located on the driving head as shown in section in Fig. 3. An anchor plate l2 having a double D opening therein conforming to the flattened section of the driving head is seated thereon against the shoulders I, '8 and is provided with a radial slot I3 for the reception of the outturned end H of a drive spring [5.

A control nut I6 is threaded on the screw shaft 4 and is provided with a radial flange I! having a notch i8 receiving the opposite end I9 of the driving spring whereby the spring forms a yielding driving connection through driving head 2 and anchor plate l2 to the control nut I6.

A barrel member 2| is arranged to surround the spring [5, anchor plate I2, and flange l! of control nut l6, and has an inturned flange 22 hearing on the outer side of the end flange i1. At its other end a thrust ring 23 seated on a reduced portion 24 of the driving head is retained in the barrel by a lock ring 25 so as to bear against the anchor plate i2 and apply an initial compressive force on the drive spring [5.

A thrust washer 26 is located on the power shaft I between the driving head 2 and screw shaft 4, serving to arrest the demeshing movement of the screw shaft, and also forming an abutment for the control nut l6 when it is pressed backward by the screw-jack action of the screw shaft and control nut, thereby limiting the compression of the transmission spring i5 as shown in Fig. 2.

In order to assist in the traversal of the pinion and screw shaft 4, a counterweight ring 21 is journalled on the hub 28 of the pinion and is pressed against the ends of the pinion teeth by means of a spring washer 29 which is maintained under compression by a lock ring 3|. Due to the frictional mounting of the counterweight 21 it also acts as a rebound check for the pinion, preventing the pinion from bounding backward toward the engine gear when it is thrown out of mesh as the engine starts.

Means for normally maintaining the screw shaft and pinion member 4 in idle position is provided in the form of a detent member 32 traversing the control nut Hi and bearing on the inclined shoulder 33 of the screw shaft under pressure of a spring member 34.

In operation, starting with the parts in the positions illustrated in Fig. l, rotation of the power shaft I is transmited through the driving head 2, anchor plate i2, and transmission spring l5 to the control nut Iii. This causes traversal of the screw shaft and pinion member i to the right until the pinion engages the stop sleeve 6 whereupon rotation of the pinion causes rotation of the engine gear 5.

When the cranking load is thus applied to the transmission spring 15, it is first compressed by the backward movement of the control nut [6 due to the screw-jack action of the screw shaft and nut, and when the control nut engages the thrust washer 26, the spring I5 wraps down on the cylindrical surfaces of the control nut and driving head, which thus form an interior support for the spring.

When the engine starts, the pinion and screw shaft member 4 is returned to its idle position with the end of the screw shaft abutting the thrust Washer 26, the counterweight 21 continuing to rotate until its momentum is dissipated, the frictional torque exerted thereby holding the screw shaft and pinion in demeshed position and preventing rebounding toward the engine gear.

Although certain structure has been shown and described in detail, it will be understood that changes may 'be made in the precise form and arrangement of the parts Without departing from the spirit of the invention.

I claim:

1. In an engine start driver, a. power shaft, a driving head fixed thereqm havingv a radial shoulder, an anchor plate with a radial slot formed therein, non-rotatablymounted on the driving head and seated against said shoulder,

a screw shaft slidably j ournalled on the power shaft having a pinion on one end movabletherewith into, and out of mesh. with a gear of an engine to be started, a .nut threaded on thescrew shaft having a flange with aradial slot formed therein, a coiled spring surrounding the driving head and nut and having out-turned ends anchored in the slots of said anchor plate and nut flange; and a barrel surrounding the spring, retaining the ends of the spring in said slots and limiting the separation of the anchor plate and nut flange so as to maintain the spring under initial compression.

2. An engine starter drive as set forth in claim 1, including further, means independent of said nut for limiting the meshing movement of the screw shaft and pinion, whereby the scraw-jack action of the screw shaft and nut compresses said.

spring.

3'. An engine starter drive as set forth in claim 1, including further, an eccentric weight ring journa'lled on the hub of the pinion, and spring means, pressing the weight ring against the ends of the pinion teeth to frictionally connect the weight ring to the pinion.

' JAMES J. DIGBY.

No. references cited. 

